The inverter is widely used today, especially in the newly developed electronic and technological products. For instance a liquid crystal display (LCD) panel or LCD TV mostly has an inverter to transform external AC to a high voltage electricity to actuate and ignite a cold cathode lamp. The conventional inverter transforms AC through a rectification unit to a pulsating current, and then adjusts to a low voltage DC through a filter capacitor or a power factor regulator. The lower voltage DC is fed into a transformer to boost the voltage. As the voltage boosting effect of the transformer is determined by inputting electricity, the output power of the conventional inverter is limited. Moreover, the conventional circuit design is complicated and costly, and the size cannot be shrunk as desired. All this hinders the design and development of the modern electronic products that have to conform to the prevailing trend of slim and light.
Therefore the inverter that directly uses pulsating current has been developed. This type of inverter eliminates the DC conversion circuit, and directly feeds the pulsating current into a transformer. It can save fabrication cost and reduce the size and make design simpler. Moreover, the transformer does not have to function under strict DC of a uniform voltage, service life is longer. However, the pulsating current exists in a minimum voltage-maximum voltage-minimum voltage fashion. When the transformer operates in the minimum voltage range, the output power is lower and cannot drive the cold cathode lamp. This results in loss of output power and decrease of total efficiency.
Moreover, due to every country has different AC specifications (such as voltages of 110V and 220V), manufacturers have to design the inverters with different specifications to suit different countries or regions. It is troublesome.